Speaker & MEMs Microphone design considerations wearable device

[waymond91]

Hello again!

As some may know, I’m laying out a wearable GPS tracker to use while I’m snorkeling/spearfishing/freediving. A feature I’m working on adding in is a simple ‘walkie talkie’ so that dive partners can easily communicate while on the surface (even being 10 meters away from your partner is enough to drown them out - the ocean is loud, your ears are often a little wonky from the diving, and often times people have a hood on).

To make matters more complicated, the enclosure has to be totally water tight, so there is no great way for sound to enter and exit the design.
I like to think of myself as pretty handy doing embedded DSP stuff, so I though it might be possible to kind just brute force the signal through the wall of enclosure.

So far I've selected a ICS-43434 for a microphone (although I'm not particulalrly attached to it, there was just availability for it last time I checked) and I’m using a MAX98357 (a la adafruit) to drive the little speaker. I am in the process of selecting a speaker. Right now I’m just looking at parts from Soberton Inc because digikey found them for me and their data sheets are pretty XD

My main concern is that the speaker will simply be too quiet. My board is getting quite cramped, so I’m hoping to keep the speaker under 20x20 mm (if not 15x15mm) and board mounted.

I was wondering if anybody had any thoughts on the matter? Are there particular speaker technologies I should look at? How big a role does mounting play in the quality? Its frustrating looking at a frequency response curve of the speakers, when surely an audio clip from the test data would be better.

One specific question I have is if I can meaningful improvements by boosting the low-frequencies in the signal digitally? For example, from what I’ve read the “core frequency” (but also the lower end) of the human voice is centered between 120-200 Hz for adults. However, most of these little speakers really drop off when lower than 1Khz.
Would digitally amplifying the low frequencies be damaging to the speaker? Would it make a noticeable difference?

Sorry to keep spamming this forum, however I’ve been getting such good feedback its starting to get addicting. I haven’t had these kind of online interactions since I was in university on DIY Drones back in 2012-2013. Now the site is mostly a market place…

[themadhippy]

How about a bone speaker instead of a normal driver.